Isobaric mass-change determination

Mass Thermogravimetry Isobaric mass-change determination TG... 

Isobaric mass-change determinations The equilibrium mass of a substance at a constant partial pressure of the volatile product(s) measured as a function of temperature while the substance is subjected to a controlled temperature program. The isobaric mass-change curve is plotted with mass on the ordinate, decreasing downward, and temperature on the abscissa, increasing from left to right. 

If one could reproduce the neutron end beta efficiencies from one mass to the next, one could use a known Pn value to determine the ratio of beta efficiency to neutron efficiency and then calculate all other Pn values using Eq. 1. With our present apparatus, the neutron efficiency is insensitive to changes from one mass number to the next, but the beta efficiency depends more critically on how the beam is tuned. We thus use Eq. 2 to calculate Pn because the beta efficiency does not appear in the expression. In some mass chains with several precursors (either isomers or isobars) it is possible to determine the beta efficiency for one of the prominent precursors from the ratio of the coincidence counting rate to the neutron counting rate. We then calculate Pn values for the other precursors in that mass chain by use of Eq. 1. In all cases we use the neutron counting efficiency determined for 9 Rb by use of Eq. 2 ond the Pn value of 13.6 0.9 X. 

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